• Journal of Information Processing Systems
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• 제8권3호
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• pp.409-420
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• 2012

The decision-making by agents in games is commonly based on reinforcement learning. To improve the quality of agents, it is necessary to solve the problems of the time and state space that are required for learning. Such problems can be solved by Macro-Actions, which are defined and executed by a sequence of primitive actions. In this line of research, the learning time is reduced by cutting down the number of policy decisions by agents. Macro-Actions were originally defined as combinations of the same primitive actions. Based on studies that showed the generation of Macro-Actions by learning, Macro-Actions are now thought to consist of diverse kinds of primitive actions. However an enormous amount of learning time and state space are required to generate Macro-Actions. To resolve these issues, we can apply insights from studies on the learning of tasks through Programming by Demonstration (PbD) to generate Macro-Actions that reduce the learning time and state space. In this paper, we propose a method to define and execute Macro-Actions. Macro-Actions are learned from a human subject via PbD and a policy is learned by reinforcement learning. In an experiment, the proposed method was applied to a car simulation to verify the scalability of the proposed method. Data was collected from the driving control of a human subject, and then the Macro-Actions that are required for running a car were generated. Furthermore, the policy that is necessary for driving on a track was learned. The acquisition of Macro-Actions by PbD reduced the driving time by about 16% compared to the case in which Macro-Actions were directly defined by a human subject. In addition, the learning time was also reduced by a faster convergence of the optimum policies.

• 한국게임학회 논문지
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• 제11권2호
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• pp.141-149
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• 2011

가상 환경에서 가상 캐릭터가 사람과 같이 자연스럽게 동작하기 위한 과정은 많은 노력을 필요로 한다. 가상 캐릭터는 행동을 기반으로 동작하기 때문에 자연스럽게 동작하기 위해서는 행동 정의가 가장 중요하다. 최근에는 사람이 조작한 가상 캐릭터의 행동을 기반으로 가상 캐릭터가 수행할 일련의 행동을 정의하는 Programming by Demonstration에 관한 연구가 활성화되고 있다. 하지만 이 방법들은 항상 동일한 길이의 연속적인 행동을 도출하거나 연속적인 행동을 정의할 때 사용하는 행동들을 제한하기 때문에 다양한 일련의 행동 생성하기가 어렵다. 자연스럽게 동작을 수행하기 위해서는 조작한 가상 캐릭터의 행동에서 최대한 다양한 일련의 행동들을 도출하고 도출한 일련의 행동들을 대표하는 최적의 연속적인 행동을 선택해야 한다. 그래서 여러 가지의 제약 사항을 줄이면서 일련의 행동을 생성하기 위한 연구들이 필요하다. 이 논문에서는 사람이 조작한 캐릭터의 행동을 수집하고 가상 캐릭터가 수행할 일련의 행동을 모두 도출해서 가상 캐릭터에게 적합한 일련의 행동을 선정하는 방법을 제안한다. 실험에서는 제안한 방법을 자동차 게임에 적용해서 생성되는 과정을 기술한다. 생성된 결과를 보면 사람이 수행한 일련의 행동을 길이나 분할하는 위치에 제약을 받지 않고 생성한 것을 볼 수 있었다. 결국, 제안한 방법은 더 많은 일련의 행동을 도출하고 가상 캐릭터에게 적합한 행동을 선정할 수 있음을 확인하였다.

• 한국멀티미디어학회논문지
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• 제11권3호
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• pp.353-363
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• 2008

단일 에이전트 환경에서는 Q-학습의 학습 시간을 줄이기 위해서 학습결과를 전파시키거나 일렬의 행동을 패턴으로 만들어 학습한다. 다중 에이전트 환경에서는 동적인 환경과 다수의 에이전트 상태를 고려해야하기 때문에 학습에 필요한 시간이 단일 에이전트 환경보다 길어지게 된다. 이 논문에서는 단일 에이전트 환경에서 시간 단축을 위해서 유한개의 행동으로 정책을 만들어 학습하는 매크로 행동을 다중 에이전트 환경에 적합한 내시 Q-학습에 적용함으로써 다중 에이전트 환경에서 Q-학습 시간을 줄이고 성능을 높이는 방법을 제안한다. 실험에서는 다중 에이전트 환경에서 매크로 행동을 이용한 에이전트와 기본 행동만 이용한 에이전트의 내시 Q-학습 성능을 비교했다. 이 실험에서 네 개의 매크로 행동을 이용한 에이전트가 목표를 수행할 성공률이 기본 행동만 이용한 에이전트 보다 9.46% 높은 결과를 얻을 수 있었다. 매크로 행동은 기본 행동만을 이용해서 적합한 이동 행동을 찾아도 매크로 행동을 이용한 더 낳은 방법을 찾기 때문에 더 많은 Q-값의 변화가 발생되었고 전체 Q-값 합이 2.6배 높은 수치를 보였다. 마지막으로 매크로 행동을 이용한 에이전트는 약 절반의 행동 선택으로도 시작위치에서 목표위치까지 이동함을 보였다. 결국 에이전트는 다중 에이전트 환경에서 매크로 행동을 사용함으로써 성능을 향상시키고 목표위치까지 이동하는 거리를 단축해서 학습 속도를 향상시킨다.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2004년도 추계 종합학술대회 논문집
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• pp.558-563
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• 2004

수많은 객체와 다양한 환경이 존재하는 가상 세계에서 에이전트의 다양한 움직임을 효율적으로 표현하는 것은 중요하다. 본 논문에서는 이러한 동작들을 사실적 표현보다는 수많은 종류의 개체들의 다양한 동작을 효율적으로 모델링하는데 중점을 둔다. 이를 위해 taxonomy에 기초한 상속 기능을 이용하고 여기에 개별동작의 특이점을 추가함으로써 효율적 모델링을 추구한다. 이를 위한 중요한 기술로서 동작들의 공통점을 추출하는 방법과 상속의 내용을 구체화 하는 방법을 개발한다. 이렇게 개발된 방법들을 네발짐승의 walk동작에 적용해보고 구체적 표현은 다관절체 표시법을 사용한다.

• 한국환경교육학회지:환경교육
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• 제18권1호
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• pp.97-109
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• 2005

This study was motivated to understand ways in which actors (students) perceived internal and external conditions of actions in determining responsibility of so-called environment friendly actions. To understand hidden reasons by which students conduct specific environmental actions more or less frequently may be more important and meaningful for environment teachers than to measure and know the frequency that their students do such actions. This study has been implemented by applying questionnaire survey to 752 ruddle school and high school students and 211 environment teachers. To test the hypothesis of this study that there would be significant differences in awareness of environment friendly actions and barriers to implementing those actions between students and environment teachers, frequency analysis and f-test have been conducted. Primary results of this study can be summarized as follows; It has been found that there were a number of evidences showing significant differences in awareness of environment friendly behavior between students and teachers. In term of action frequency, significant differences have been observed in 11 of the listed 20 actions. Similar resulted have been found in terms of perceived difficult, perceived effectiveness, and perceived guilty. These results seem to support an argument that the current list-making and checklist style of connecting students to so-called environment friendly actions need to be reviewed in a critical manner.

• 충청수학회지
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• 제19권4호
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• pp.437-443
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• 2006

We study free actions of finite groups on the 3-dimensional nilmanifold for Type 1 and classify all such group actions, up to topological conjugacy. This work supplies missing one in [1, Theorem 3.11.].

• 충청수학회지
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• 제20권3호
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• pp.223-230
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• 2007

We study free actions of finite groups on the 3-dimensional nilmanifold and classify all such group actions, up to topological conjugacy. This work generalize Theorem 3.10 of [1].

• 대한수학회보
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• 제58권1호
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• pp.133-146
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• 2021

For pseudo-free and recurrent self-similar groups, we show that continuous orbit equivalence of inverse semigroup partial actions implies continuous orbit equivalence of group actions. Conversely, if group actions are continuous orbit equivalent, and the induced homeomorphism commutes with the shift maps on their groupoids, we obtain continuous orbit equivalence of inverse semigroup partial actions.

• Nuclear Engineering and Technology
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• 제47권2호
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• pp.187-195
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• 2015

Human-induced initiating events, also called Category B actions in human reliability analysis, are operator actions that may lead directly to initiating events. Most conventional probabilistic safety analyses typically assume that the frequency of initiating events also includes the probability of human-induced initiating events. However, some regulatory documents require Category B actions to be specifically analyzed and quantified in probabilistic safety analysis. An explicit modeling of Category B actions could also potentially lead to important insights into human performance in terms of safety. However, there is no standard procedure to identify Category B actions. This paper describes a systematic procedure to identify Category B actions for low power and shutdown conditions. The procedure includes several steps to determine operator actions that may lead to initiating events in the low power and shutdown stages. These steps are the selection of initiating events, the selection of systems or components, the screening of unlikely operating actions, and the quantification of initiating events. The procedure also provides the detailed instruction for each step, such as operator's action, information required, screening rules, and the outputs. Finally, the applicability of the suggested approach is also investigated by application to a plant example.

• 생약학회지
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• 제26권2호
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• pp.139-147
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• 1995

Crinum asiaticum var. japonicum is a wild plant growing only in Jeju-island, Korea, and in Japan. The whole part of this plant has been known to have the pharmacological actions such as analgesic, anti-inflammatory, platelet-aggregation inhibitory, antitussive, and expectorant. With these assumed actions, the leaves (Crinum folium) of this plant has been used in the folk remedies for arthritis and arthralgia. There is, however, no scientific evidences for the pharmacological actions of Crinum asiaticum var. japonicum. In the present study, the analgesic, anti-inflammatory, and platelet-aggregation inhibitory actions of Crinium folium were evaluated using writhing test, tail-flick test, carrageenin antiedema test, in vitro thromboxane $B_2$ quantitation assay and in vitro platelet aggregation test. In order to obtain the partially purified fraction whose pharmacological action is excellent, the methanol extract of Crinium folium was fractionated consecutively into four biological fractions such as ether, ethyl acetate, butanol, and water fractions and their pharmacological actions of the fractions were investigated. Putting our results together, Crinium folium, especially ethyl acetate fraction was proven to have significant analgesic, anti-inflammatory and platelet-aggregation inhibitory actions by inhibition of prostanoids biosynthesis as one of its mechanism of action.